The process and predictors of drug and alcohol abstinence among adolescents with substance use disorders (SUD) remains a critical area for research. A growing body of research on adults with SUD suggests that religious and spiritual (R/S) processes play an influential role in supporting recovery over time, such that higher levels of R/S predict better substance use outcomes. These findings are consistent with the 12-Step model of recovery, which posits that the primary mechanism through which recovery occurs is a spiritual awakening. They are also consistent with theoretical models that highlight the importance of reconnecting with sources of meaning, purpose, and values as central to long-term recovery from SUD. However, investigation into the role of R/S in adolescent SUD treatment response remains scarce and the available research contains methodological limitations (i.e., lack of post-treatment follow-up, correlational designs). The proposed study seeks to advance knowledge of the role of R/S among adolescents in SUD treatment through secondary data analyses of two adolescent outpatient samples and collection of original qualitative data that will be used to help interpret quantitative findings and generate new hypotheses to be tested in future research. The proposed project will enhance existing knowledge by using a prospective design and follow-up periods that extend beyond the end of formal treatment (i.e., 9- and 12-month follow-ups). The aims of the project are (1) to examine the predictive value of baseline R/S and during-treatment change in R/S on later substance use and mental health outcomes, (2) to examine the psychometric properties of a new measure of spirituality and its ability to predict outcomes, and (3) to use qualitative data to explain and contextualize quantitative findings. Problem recognition will be examined as a potential moderator of outcomes, based on research that suggests adolescents who believe they have a problem with drugs or alcohol are more likely to get involved in spiritually-oriented 12-step groups. The proposed research and training plan will provide the PI with training in (1) theoretical models of R/S in relation to health behavior, (2) advanced quantitative and qualitative research methods, (3) processes of SUD recovery, (4) evaluation of measurement tools, and (5) scientific writing and research dissemination. Importantly, the proposed project will provide directions for the PI's future research on the role of R/S in addiction recovery. This research has direct implications for clinical practice, as it will help clinicians understand whether to proactiely integrate and support their adolescent clients' religious beliefs and foster spiritual growth as pat of treatment. It will also help clinicians understand the potential benefits of involvement in spiritually-oriented 12-Step organizations, which could impact their referral practices and 12-step facilitation efforts. Greater knowledge about the role that R/S plays for young people during and following treatment will enhance the specificity and efficiency of treatment for this challenging population and ultimately foster strengths that enhance the chances of remission and recovery.